This application relates to turbomachinery and, in particular, to an air operated screw jack device for installing a tapered wedge slide under a tapered dovetail stator wedge in the stator core of a turbine generator.
Magnetic stator cores for turbine generators typically include radially oriented slots that extend axially along the length of the core. Armature windings are seated within the slots and are held in place by a slot support system that includes tapered stator dovetail wedges and slides, various solid and conforming fillers, and a top ripple spring. These support components are employed in order to maintain the stator armature windings in a radially tight condition within the slots. The tapered dovetail wedges are received within axial dovetail slots on opposite side walls of the radial slots. During the process of tightening the stator wedges, it is necessary to install a complementary-shaped, tapered wedge slide against each stator wedge. For the sake of convenience, reference will be made herein to xe2x80x9cstator wedgesxe2x80x9d that are seated in the dovetail slots and xe2x80x9cstator slidesxe2x80x9d that are used to tighten the wedges. The stator slide is pre-gauged and pre-sized to have a significant interference fit relative to the slot contents, i.e., the windings, fillers and ripple springs. The force required to install the stator slide may be several thousand pounds.
Several methods have been used to provide force required to install the stator slides. For example, stator slides have been manually installed using a drive board and a large hammer, and using a modified pneumatically operated riveting gun. These methods, however, are time consuming and place considerable strain on the operator. They also subject the operator to the risk of repetitive motion injury and/or hearing damage, and pose a risk to the integrity of the stator core and armature windings.
This invention provides a new stator slide driver device that provides a smooth, controlled, non-impacting stator slide assembly technique, with significant reduction or elimination of the aforementioned risks.
More specifically, this invention provides a stator slide driver tool that utilizes a predisposed hole in an adjacent already tightened stator wedge to provide the reaction point for the stator slide driving force. In one exemplary embodiment, a commercially available air wrench is utilized to drive a lead screw which, in turn, causes a force application cart to move axially in one of two directions, depending on the direction of rotation of the lead screw. The tool includes an adjustable pin, spaced axially from the cart, and adapted to be received in a hole in the adjacent and already tightened stator wedge. In use, the cart is located so that an upstanding flange of a drive block abuts the rearward end of a stator slide loosely located under a stator wedge adjacent an already tightened stator wedge in which the pin is inserted. Actuation of the air wrench will cause the cart and its force application flange to drive the stator slide under the stator wedge, without repetitive impact, to thereby tighten the wedge, using the adjacent already tightened wedge as a force reaction point.
Accordingly, in one aspect, the present invention relates to a process for installing a tapered stator slide under a tapered dovetail stator wedge in a radial slot of a stator core assembly comprising:
a) loading windings in the radial slot, the slot having axially extending dovetail grooves in opposing sidewalls thereof;
b) loading at least one stator wedge in the dovetail grooves of the slot, and tightening the at least one stator wedge with said stator slide;
c) loading at least one additional stator wedge in the dovetail grooves;
d) locating at least one additional stator slide relatively loosely under the additional stator wedge; and
e) using the at least one stator wedge as a reaction point, applying a force to the additional stator slide to drive the additional stator slide under the additional stator wedge.
In another aspect, the invention relates to a tool for driving a stator slide under a stator wedge within a radial slot of a stator core comprising a frame including a pair of elongated rail members; a force application cart located between the rail members, the force application cart having a force block thereon; a drive connected to the frame, substantially intermediate opposite ends of the frame; a lead screw threadably engaged at one end with the force application cart and connected at an opposite end to the drive such that the drive rotates the lead screw when actuated, rotation of the lead screw causing axial movement of the force application cart and the force block; and a pin for locating the tool relative to the stator slide, and for establishing a reaction point for forces applied by the drive block.